The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 3,558,136 (McFarland) discloses a double jigsaw puzzle game wherein two opposing players or teams are provided with identically cut and illustrated, but differently colored, pieces of a scene. A playing board is provided which also includes the scene depicted by the assembled playing pieces. Each player starts with one of the opposite edge portions of the scene on the board and attempts to complete a major portion of the scene by placing the pieces properly on the board in advance of his opponent. As a player progresses with the placement of contiguous pieces of the puzzle, he is credited with scores as indicated on certain of the puzzle pieces. Further there is provided a plurality of playing pieces for each player which he may advantageously place on indicated sections of the puzzle scene as such sections are completed by the player. A starting strip is formed along each of two opposite sides of the board, the inner edges of these strips interlocking with puzzle pieces having a complementary configuration.
U.S. Pat. No. 3,682,479 (Miller et al.) discloses a three dimensional puzzle formed of several, similarly or differently colored, stacked layers of interlocked puzzle segments with each layer containing one or more voids through which portions of the layers beneath it and the interior surface of a supporting tray are visible to produce a pleasing visual effect.
U.S. Pat. No. 4,469,331 (Rinker) discloses a three dimensional jigsaw comprised of a plurality of single-layered and multi-layered interlocking puzzle pieces which combine to form, when the puzzle is assembled, a plurality of superimposed, concentric planer layers of differing surface area. When the puzzle is properly assembled, a continuous homogenous pictoral illustration is displayed on the surface of each visable planar layer of the puzzle.